Method of making heat exchangers



I B. LEWIS METHOD OF MAKING HEAT EXCHANGEBS-' j Jam 27, 1942. 2,271,431

Filed Jan. 26, 1939 INVENI OR.

' BENNETT Lgy/s' BY M A, j ATTORNEY;

Patent ed Jan.27, 1942 I 2 271 437 UNITED STATES PATENT OFFICE METHOD OF MAKING HEAT EXCHANGERS Bennett Lewis, Indianapolis, Ind. Application January 26, 1939, Serial No. 252,862

7 Claims. (or. 113-118) My invention relates to heat-transfer equipdrained, these openings are then closed in any ment and, in particular, to a. method of forming suitable manner. a conduit for a fluid which either absorbs or The accompanying drawing illustrates my inemits heat in the operation of. the equipment. vention: Fig 1 is an isometric view of an evap- An example of such a conduit is one form of 5 o a or formed to prov de W thin it an upward y evaporator used in refrigeration apparatus. opening compartment for the reception of sub- It has heretofore been proposed to make evaD- stances be cooled; Fig} 2 is f a en a Ver- 7 orators of this type with sheet-metal walls of tical section through a wall of the evaporator double thickness, the two walls being formed shown in Fig. 1; Fig. 3 is a generally horizontal to provide between them a space forthe refrig- 1 section through one corner of the {evaporator erant. In' some cases, this space has taken the shown in Fig. 1; Fig. 4 is an elevation illustrating form of a helical or retroverted channel succesthe position occupied by the evaporator of Fig. 1 sive passes or which are separated by bringing when it is to be dipped in the bath of sealing the two thicknesses of the evaporated wall into u s a c F 5 is an isometric View Of a m contact with each other. In cases where some fle const Partially p ed; and Fi 6 leakage of the refrigerant directly from one pass is a rragmental section on the line 6-5 of Fig. 5. of such a channel to an adjacent pass is of no The. evaporator illustrated in Fig. l is in the particular moment, this construction has proved form of an open-top rectangular receptacle havsatisfactory; but, because of the dimculty of proing side walls 10, desirably of sheet-metal. Exvidingan'efiective seal between successive passes tending around the S de wa o the p of the channel, it has heretofore been regarded 01B is Strip ll of Sheet-metal formed w p as unsatisfactory for use in situations where it is allel gro ves and h ving its ends brou ht t necessary or desirable to ensure that all the ree indicated M in c a man e a frigerant flows throughout the entire length or the grooves o a ous helical pass e 3 the channel. about the receptacle. As shown 'in the drawing,

It is the object of my invention t m two of the strips H are pro 'ded, one disposed a device the type described in which an drew near the bottom of the receptacle and the other tive seal is provided between successive passes 11951 the p. the Pas ges l3 formed by the strips of the refrigerant-channel so that by-passing of being intermnnected in series a conduit the refrigerant vWithin the evaporator will be and'provided with inlet .and outlet fittings Ii eliminated. A further object of my invention is and ion into ,the refrigerating systo protect the device against corrosion.

m embodying my mvenuon m f ig t I Between successive turns of the passage l3, the

evaporator, 1 or the evgpomtor with walls of material of the strip II is brought into contact double-thickness in such a way that between the 5 with the side indicated at m and walls there is provided a continuous refrlgerantsecured thereto desirably by welding tr?? e having stretches which are contiguous The is pmvmed with openings and generally arall l, u h stretches being that when the strip is wrapped around are-ted by bringing the walls into contact between the receptacle the openings he at diagonal than m 1 cause to now throughthemfm; oppoflte corners or the receptacle and will pro- ,H W13 1mm V videcommunication-betweenthepassage l3 and t cewmchwmtheatmospheraflterthestriporstripsll become dgmmmbetwm I havebeensecuredinplace,thereoeptacleisiinstretches of the e andwill se ve later to mung the WW preventbreetsimmyrigerant-flowrromone the "19mm 13 mm cated mm. 4 that the diagonalbetweenthe m? m is twosets or openings I1 is approximately vertical. zinc,which.inaddiflontoitsseallngfunctlnn, nusthe gfingsubstgncemgymtermhtum alsoresistsoorrosion. Thezinciscausedtoflow gthepasagellthroughthelowermostopening through the refrigerant-e by so l1therein,theairdisp1aoedbytheenteringsealthecompleteevaporatormabathot moltenzlnc. ingsubstanoe escaping throughtheother opentheebeingprovided at suitablelocations inglj atthefnpofthereceptsale. Hthedevice withfortheentryofthemoltmaine -isrorinedofsheet-steel.'moltenzincisasatisandtortheegressotair. fiterthedipni l-opiactorysealins. oration slim Afie thereceptaclehasbemimmersedfora in Fig. 6 and the right-hand end of Fig. 5.)

sufficient length of time, it is withdrawn and held in the position illustrated in Fig. 4 to permit undeposited sealing substance to drain from its surface and from the surfaces of the channel I 3. After the draining operation is completed, the

, openings l1 are closed.

Conveniently, the openings l1 are provided in the bottoms of recesses l8 formed by inward displacement of the material of the strip each opening I! being somewhat smaller in diameter than its associated recess. To seal each opening IT, a disc IQ of suitable material may be placed in the recess l8 and secured therein as by welding, soldering, or brazing.

An evaporator such as that described above possesses a continuous helical refrigerant-passage |3, the several turns of which are sealed from each other by the sealing substance deposited in the joint I6 as a result of the immersion above described. Cross-flow between adjacent turns of the helical passage isprevented, and all the refrigerant is compelled to flow through the passage from one end thereof to the other. ther, the metal of which the evaporator is formed is protected against corrosion by the zinc with which it is coated.

In the arrangement illustrated in Figs. and 6, the device comprises two sheet-metal plates 2| and 22. The plate 22 is formed with spaced, parallel ribs 23 each ,of which extends inwardly from one end of the plate and terminates short of the opposite end to leave a short unribbed portion 24. The portions 24 are arranged alternately at opposite ends of the plate 22.

After the plate 22 has been formed in the manner described it is brought together with the plate 2| which closes the open tops of the channels between adjacent ribs 23. The two plates are then secured together, as by welding the ribs 23 to the face of the plate 2|. Inlet and outlet fittings 26 and 21 are mounted in the ends of the outside channels.

The assembly thus formed is dipped in the sealing compound while held in positionwith the ribs 23 extending generally vertically, the sealing compound entering the channels at the lower Furends thereof beneath the unribbed portions 24 of the plate 22 and displacing air which escapes from the upper ends of the channels. After immersion, excess sealing compound is drained off, and the edges of the unribbed portions 24 are brought into engagement with and secured to the plate 2|, as by welding. (See dotted lines y 23 a continuous this operation, the channels between the ribs are connected in series to f0; retroverted passage.

I claim as my invention:

1. A process of making a heat-exchanger, comprising iorming a plate of flexible material to provide a series of parallel ribs separated by opentopped channels, covering the open tops of said -channels with a second plate engaging said ribs While leaving openings at the ends of said channels, securing said second plate to said ribs, im-' mersing the assembly in a bath of liquid sealing material with some of said openings at the bottom of the assembly and others at'the top and with the channels extending generally vertically between the upper and lower openings whereby the liquid sealing material may enter the lower openings and fill the channels while air escapes from the upper openings, removing the assembly.

from the bath to drain any excess sealing material from the channels through the lower opensaid openings at diametrically opposite points of said container, bringing the ends of said plate together so that one end of each channel is allned with the opposite end of an adjacent channel whereby the channels are connected together in series, securing the plate to the container and sealing the joint between its ends, immersing the container in a bath of liquid sealing compound in a position such that the diameter joining such openings is approximately vertic al whereby the sealing material may enter the lowermost of said openings while air escapes through the uppermost openings, removing the assembly from the bath of liquid sealing compound to drain any excess sealing compound through the lowermost of said openings while air enters the uppermost of said openings, and subsequently closing said openings.

' 3. A process of making a heat exchanger, which comprises forming aplate of flexible material with a series of parallel spaced ribs separated by open-topped channels, each of said ribs extending inwardlyfrom one end of they plate and terminating short of the other end to leave an unribbed portion, said unribbed portions being disposed alternately at opposite ends of the plate, covering the open tops of said channels with a second plate spaced from said unribbed portions of the first plate to leave openings at the opposite ends of each channel, securing said second plate to said ribs, immersing the assembly in a bath of liquid sealing material with the ribs extending generally vertically whereby liquid'sealing material may' enter the channels through the openings at the lower ends thereof while air escapes from the channels through the openings at the upper ends thereof, removing the assembly from the bath to drain excess sealing material from the channels through the openings at the lower ends thereof while air enters the openings at the upper ends thereof, bending the edges of said unribbed portions into association with said second plate, and sealing the joints between such edges and the second plate to interconnect said channels in series.

4. The invention set forth in claim 1 with the addition that said plates are of sheet-metal and said sealing material is molten zinc, said ribs being secured to said second plate by welding.

5. The invention set forth in claim 2 with the addition that said plates are of sheet-metal and walls of said channels, wrapping said plate about a container having side walls which close said points of said container,

- tainer in a bath of liquid open-topped channels posing said openings plate together openings is approximately sealing material may enter the lowermost of said openings while air escapesthrough the uppermost openings, removing the assembly from the bath of liquid seaiing compound to drain any excess sealing'compound through the lowermost of said openings while air enters the uppermost of said openings, and subsequently closing said openings.

v BENNETT mawrs.

vertical, whereby the 

